Sen lisäksi, että tulokset esittelevät syitä harmonisiin yliaaltoresonansseihin tuulipuistossa, ne korostavat moodianalyysimenetelmän mahdollisuuksia sähköverkkojen resonanssien laskemisessa. Tulokset tuovat myös uusia näkökulmia moodianalyysin jatkokehittämiseen resonanssianalyysissa.Modern power networks have a growing number of power electronic devices, some of which can be seen as sources of harmonic currents. Moreover, the electric grids have numerous inductive and capacitive elements forming ideal conditions for harmonic resonances. These resonances, however, are a severe threat to power quality and the function of power systems. For this reason, the resonance analysis is an emerging topic in the field of power systems.

In the current study, two analytical methods are used: a frequency scan and harmonic resonance mode analysis. Although the former method is well-known, the latter method is relatively new. The mathematical bases of these two methods are introduced in the theoretical section and then applied in the simulations of an aggregated model of an off shore wind power plant.

The work has two principal objectives: to determine the main reasons for harmonic resonances in a wind power plant and to investigate the applicability of the harmonic resonance mode analysis to analyse the resonances.

In addition to establishing the resonating elements in a wind power plant, the results reveal the harmonic resonance mode analysis to be a plausible tool for the systematic resonance analysis of power networks. The thesis offers new aspects of developing the modal approach to the resonance studies are provided.